The axial tip clearance leakage analysis of the winglet and composite blade tip for the liquid-ring vacuum pump

Abstract

Axial tip clearance leakage of liquid-ring vacuum pump has an important impact on it's hydraulic performance. In order to suppress the axial tip clearance leakage flow and improve the hydraulic performance, the winglet and composite blade tip were introduced to the axial tip clearance of the 2BEA-203 liquid-ring vacuum pump blade. The mechanisms of the winglet and composite blade tip on the clearance leakage flow field were analyzed by numerical simulation method. The analysis results show that the winglet extends the flow channel of axial clearance, and reduces the pressure difference between the two sides of the clearance, thus suppressing the leakage flow. Therefore, the winglet impeller can improve the pump vacuum and efficiency to a certain extent. However, the suction surface winglet will generate the wing corner vortex under the winglet, resulting in additional losses and making the improvement of its hydraulic performance lower than that of the pressure surface winglet. For the composite blade tip, the jet hole directly leads the high-pressure fluid from the pressure surface to the clearance, which weakens the effect of the winglet. So, the suppression effect of the composite blade tip is lower than that of the winglet. Although the winglet reduces the mixing loss of the jet, the suppression effect of the winglet is better than that of the jet. Therefore, as the mechanism of the winglet is different from that of the tip jet, the suppression effect of the composite blade tip is lower than that of the winglet, and greater than that of the tip jet.